Abstract: In this work, a new method of ultrasonic assisted foam separation to effectively enrich bovine serum albumin(BSA) from its aqueous solution had been developed. Firstly, Fourier transform infrared spectroscopy(FTIR) was used to investigate the molecular structure changes of BSA before and after foam separation, and high performance size exclusion chromatography was used to determine the effect of ultrasonic wave on BSA aggregation. Then, the effects of liquid height, volumetric air flow rate and pore diameter of gas distributor on the efficiency of foam separation in the recovery of BSA were studied, respectively. The physicochemical properties of the recovered BSA were evaluated. The results indicated that the adsorption of BSA on the gas-liquid interface during foam separation would induce the generation of intermolecular disulfide bonds, and the BSA aggregation was effectually inhibited by ultrasonic wave. Under the suitable operation conditions of temperature 25℃, pH6.0, casein concentration 0.20 g/L, pore diameter of gas distributor 180 μm, liquid height 300 mm, feed feeding rate 2 mL/min, volumetric air flow rate 150 mL/min, ultrasonic power 600 W and ultrasonic treatment time 2 min, the enrichment ratio and recovery percentage of BSA were 6.3% and 85.3%, respectively. Furthermore, the surface hydrophobicity, foam properties and emulsification of BSA solution were significantly improved by ultrasonic treatment through inhibiting the production of BSA aggregation during the foam separation.